Chloroalkenyl thiopyridine oxides



United States Patent 3 150 145 cnLoRoArKENrr. rrhorrmnmn 0XIDES Herbert L. Rawlings, Scott Depot, and John J. DAmico, Charleston, W. Va., assignors to Monsanto Company,

a corporation of Delaware No Drawing. Filed May 1, 1959, Ser. No. 810,225 Claims. (Cl. 260-294.8)

S-R \Nl in which R represents a lower alkenyl group, preferably halogen substituted lower alkenyl. They are prepared by condensing the sodium salt of 2-pyridinethiol, l-oxide with the corresponding unsaturated halide. Suitable reactants comprise allyl chloride, methallyl chloride, cis-l,2,3-trichloro-2-butene, trans-1,2,3-trichloro-2-butene, 1,3-dichloro-Z-butene, 2,3-dichloro-1-propene, 2,3-dibromo-1- propene, 1,3-dichloropropene, l-chloro-3-iodo-2-propene, 1,3-diiodo-2-butene, 2,3-diiodo-2 butene, 3 bromo-lchloro-Z-fluoro-l-propene, cis 1,2,3 trichloro-l-propene, trans-1,2,3-trichloro-l-propene, 1,4-dibromo-2,3-dichloro- Z-butene, 1,2,3,3-tetrachloropropene and 2,3,3-trichloro-1- butene. The last readily undergoes an allylic rearrangement and is therefore equivalent to 1,2,3-trichloro-2- butene.

The following examples illustrate in detail the preparation and properties of some of the new products but are not intended as a limitation of the invention.

EXAMPLE 1 To a stirred solution of 30 grams (0.2 mole) of the sodium salt of 2-thiopyridine, l-oxide in 100 ml. of water was added in one portion 22.2 grams (0.2 mole) of 2,3- dichloro-l-propene and the mixture heated at 5060 C. for 24- hours. After cooling to C., 300 ml. of ether were added and stirring continued for minutes at 5-l0 C. The precipitate which formed was filtered and air dried at room temperature. After recrystallization from ethyl alcohol, the 2-(Z-chloroallylthio)pyridine, l-oxide was obtained as a tan solid, MP. 114-115 C. Analysis gave 7.4% nitrogen, 15.6% sulfur and 17.6% chlorine as compared to 7.0% nitrogen, 15.9% sulfur and 17.6% chlorine calculated for C H ClNOS.

EXAMPLE 2 In this example 2-broino-3-chloro-1-propene was used in place of 2,3-dichloro-1-propene. The mixture was heated at 50-60 C. for 5 hours, then cooled to 10 C. and 58-0 ml. of ether added. Stirring was continued at 0-10 C. for minutes. The precipitate which formed was filtered, washed with water until neutral to litmus and air dried at room temperature. After recrystallization from ethyl alcohol the 2-(2-bromoallylthio) -pyridine, l-oxide was obtained as a tan solid, MP. 122-123 C. Analysis gave 5.3% nitrogen and 13.3% sulfur as compared to 5.7% nitrogen and 13.0% sulfur calculated for C H BrNOS.

EMMPLE '3 To 30 grams (0.2 mole) of the sodium salt of 2-thiopyridine, l-oxide in 100 ml. of water was added in one portion with stirring 22.2 grams (0.2 mole) of 1,3-dichloropropene and the mixture heated at 50-60 C. for

24 hours. After cooling to 25 C., 300 ml. of ether was added and the solution stirred for one hour. The ether and aqueous layer were then decanted and the bottom oily layer placed in vacuo at a maximum temperature of C. at 1-2 mm. The 2-(S-chloroallylthio)pyridine, 1- oxide thus obtained was an amber oil analyzing 6.5% nitrogen and 15.2% sulfur as compared to 6.9% nitro gen and 15.9% sulfur calculated for C H ClNOS.

EXAMPLE 4 In the procedure of Example 3, 1,1,3-trichloropropene was substituted for the 1,3-dichloropropene. The 2-(3,3- dichloroallylthio)pyridine, l-oxide was a dark amber oil analyzing 13.4% sulfur as compared to 13.6% calculated for CaH'ZClzNOS- EXAMPLE 5 Substitution of cisand trans-1,2,3-trichloropropene in this example gave 2-(cisand trans-2,B-dichloroallylthio)- pyridine, l-oxide as a dark amber oil which became a semi-solid on standing. Analysis gave 5 .8% nitrogen and 13.7% sulfur as compared to 5.9% nitrogen and 13.6% sulfur calculated for C l-i Cl NOS.

The new compounds of this invention have general herbicidal properties but are particularly effective as preemergent herbicides in a wide range of crops and weed species. The method of controlling vegetation, according to this invention, comprises applying thereto a toxic concentration of the above-defined alkenyl thiopyridine oxides. By applying the toxicants to vegetation is meant any means whereby the toxicant is brought into contact with living plants. The toxicant may be applied conveniently in the form of a spray containing the active ingredient in a concentration within the range of 0.1%- 10.0% by weight. Thorough coverage of the foliage is effective for contact killing. For pro-emergence control amounts within the range of /2-60 pounds per acre have been used successfully.

In general, in the application of these compounds, aqueous dispersions or aqueous solutions depending on whether or not the compound is water soluble, will be found most desirable. The dispersions will of course contain a dispersing or wetting agent and the solutions also preferably contain wetting agents to facilitate the spreading of the solution. As dispersing and wetting agents there may be employed soft or hard sodium or potassium soaps, alkylated aromatic sodium sulfonates such as sodium dodecylbenzenesulfonate, or an amine salt of dodecylbenzenesulfonic acid, alkali metal salts or sulfated fatty alcohols, ethylene oxide condensation products of alltyl phenols or tall oil and other dispersing and wetting agents.

The tables below illustrate characteristic herbicidal activity of the compounds of this invention. The toxicant was emulsified in water and the emulsion applied as a spray. In the pro-emergence tests the spray was applied to the ground of seeded plots before the grass or other plants emerged. The alkenyl thiopyridine oxide was applied at the rate of 25 pounds per acre and the phytotoxicity observed. In the foliage tests the spray containing the concentration of the active ingredient shown in the table was applied to the foliage of grass and to the foliage of bean plants and finally to the foliage of a mixture of broad-leaved plants and the effect recorded. The following phytotoxicity rating key was used:

The plants employed in the pre-emergence tests are designated by letter in Table I. The plants correspond ing to the letters are as follows:

l-Foxtail K-Barnyard grass LCrab grass MPigweed N-Wild buckwheat AMorning glory B-Wild oats C-Brome grass D--Rye grass ERadish-rnustard Aqueous dispersions of the toxicants within the afore- FSugar-beet O-Tomato said concentration were applied to wheat plants four. days G C tton P S0rghurn 10 after infection with the fungus. After a week the plants H-Corn were examined and graded as to number and size of Table I PRE-EMERGENCE Phytotoxieity rating Compound I A D O D E F G H I K L M N O P ProductofExamplel 0 3 3 3 O 2 0 3 3 2 3 3 Product ofExample 2 0 3 2 3 0 1 1 3 3 1 3 1 Product of Example 3. 0' 1 2 3 0 2 2 3 3 2 Product of Example 1L. 3 3 3 1 3 3 3 3 1 0 3 Product of Example 5 2 3 3 1 3 3 3 3 3 2 3 Product of Example 6 0 l 2 2 3 3 3 3 Table II pustules formed on the leaves. Fair to excellent control 30 was observed. 7 CONTACT It is intended to cover all changes and modifications of the examples of the invention herein chosen for purposes Phytotoxieity ratin" Active ingredient Cone, b of disclosure which do not constitute departures from percent the spirit and scope of the invention.

Grass Bean Broadleaf 35 What is Claimed is:

1. A compound of the formula Product of Example 1 0.5 1 3 3 0.2 1 1 2 Product of Example 2--.... 0.5 1 2 2 Product of Example 3 [1] g ProduetofExample4 015 2 a 3 4O ,S-oH,-oX=oYo1 0.2 0 3B 2 N Product of Example 5 0. 5 1 3 3 J,

Product Examples 1 2 2 where X and Y are selected from a group consisting of hydrogen and chlorine. 4,5 2. 2-(2,3,3-trichloroallylthio)pyridine, l-oxide.

Employed at lower concentrations the herbicidal compositions of this invention may be applied to crop plants to give substantially complete control of certain weeds without harming the crop plants. In applying the herbicidal compositions for selective weed control, the applications are preferably of the pie-emergence type. At a concentration of 5 pounds per acre, for example, the compositions show a highly selective action against crab grass and pigweed in the presence of such common crops as radish, cornand cotton.

3. 2-(3-chloroallylthio)pyridine, l-oxide. 4. 2-(3 ,3-dichloroallylthio) pyridine, l-oxide. 5. 2-(2,3-dichloroallylthio)pyridine, l-oxide.

References Cited'in the file of this patent UNETED STATES PATENTS 2,679,453 Brett et a1. May 25, 1954 2,826,585 Cislak Mar. 11, 1958 2,826,536 Cislalc Mar. 11. 1958 2,875,031 Kruckenberg et a1. Feb. 24, 1959 

1. A COMPOUND OF THE FORMULA 